CompositesWorld
Issue link: https://cw.epubxp.com/i/841219
JULY 2017 32 CompositesWorld INSIDE MANUFACTURING Decade-long developmental effort reaches key wind energy cost-reduction milestone using epoxy-besting infusion resin. » Wind turbine blades remain a key market segment for compos- ites. According to the new report "Wind Turbine Composites Material Market: Global Trends & Forecast to 2020" by Markets- andMarkets (Magarpatta City, India and Seattle, WA, US), the market for composites in wind turbines — comprising mainly nacelles and rotor blades — totaled US$7.2 billion in 2015 and is expected to grow at a CAGR of 9.3% to reach US$12.2 billion by 2021, thanks especially to increasing demand in China, India, South Korea and Japan. e wind industry consultancy MAKE (Chicago, IL, US and Aarhus, Denmark) estimates that roughly 650,000 wind turbine blades will be produced between 2017 and 2025, with a 12-15% increase in the average rotor diameter. "Blade lengths continue to increase," says MAKE partner Dan Shreve, "offering an enormous market opportunity for blade OEMs and their strategic materials providers." A key facet of that opportunity is to find new ways to reduce blade cost. Although the cost of building and operating wind turbines has decreased significantly over the past two decades, "blades are still 25-35% of the total wind turbine cost," says Covestro's (Leverkusen, Germany) Kim Harnow Klausen. Klausen is the head of Covestro's program to develop polyure- thane (PU) as an optimized matrix resin for composite wind blade production. Begun in 2009, the program produced a demon- strator glass fiber/PU spar cap for a 45m long wind blade — the focus of this article — using resin infusion in 2015. "We have now made the first poly- urethane wind blade in Asia, a 37.5m long blade for a 1.5-MW wind turbine in China," says Klausen. For this blade, all of the components — spar, web, root and shell — were infused using Covestro's PU resin. "We are also going to make a larger blade this year," he adds. Why polyurethane? "e resin we have developed is 10-25% stronger than epoxy," Klausen claims. PU also offers inherently lower viscosity — below 100 cps at 25°C — for faster infusion, as well as a faster cure and less exotherm during cure vs. epoxy, vinyl ester (VE) and polyester systems. Further, as blade length increases, so does the need for improved properties and fatigue performance, as well as fabrication speed. MAKE sees the potential of polyurethane in blade production. "We have identified this as an early-stage material advancement Polyurethane's processing speed, properties enable bigger blades PU infusion resin for wind blades Polyurethane specialist Covestro (Leverkusen, Germany) has developed a PU infusion resin — soon to be the first certified for wind turbine blades by DNV GL — aimed at cutting production cost by 10-15% while also reducing weight and enabling high performance at increasing lengths. Source | Covestro By Ginger Gardiner / Senior Editor